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  <script>
    let arr =[3,4,9,2,7,5]
    //数组的filter方法，作用是筛选出符合条件的元素
    let res =arr.filter(item =>{

      // console.log(item)数组中每一项
      return item > 4
    })
    console.log(res)
  </script>
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